The new ferry terminal on the Key System Mole in 1933. The old ferry terminal and the end of the mole had been destroyed by a fire and explosion earlier in the year.

The system was a consolidation of several streetcar lines assembled in the late 1890s and early 1900s by Francis Marion "Borax" Smith, an entrepreneur who made a fortune in his namesake mineral, and then turned to real estate and electric traction. The Key System began as the San Francisco, Oakland, and San Jose Railway (SFOSJR), incorporated in 1902. Service began on October 26, 1903 with a 4-car train carrying 250 passengers, departing downtown Berkeley for the ferry pier. Before the end of 1903, the general manager of the SFOSJR devised the idea of using a stylized map on which the system's routes resembled an old-fashioned key, with three "handle loops" that covered the cities of Berkeley, Piedmont (initially, "Claremont" shared the Piedmont loop) and Oakland, and a "shaft" in the form of the Key pier, the "teeth" representing the ferry berths at the end of the pier. The company touted its 'key route', which led to the adoption of the name "Key System".

In 1908, the SFOSJR changed its name to the San Francisco, Oakland & San Jose Consolidated Railway, changed to the San Francisco-Oakland Terminal Railway in 1912. This went bankrupt in December 1923 and was re-organized as the Key System Transit Co., transforming a marketing buzzword into the name of the company.

A Key System train in Oakland, 1909

Following the Great Crash of 1929, a holding company called the Railway Equipment & Realty Co. was created, with the subsidiary Key System Ltd running the commuter trains. In 1938, the name became the Key System.

The same year E. Jay Quinby hand published a document exposing the ownership of National City Lines (General Motors, Firestone Tire, and Phillips Petroleum). He addressed the publication to The Mayors; The City Manager; The City Transit Engineer; The members of The Committee on Mass-Transportation and The Tax-Payers and The Riding Citizens of Your Community. In it he wrote This is an urgent warning to each and every one of you that there is a careful, deliberately planned campaign to swindle you out of your most important and valuable public utilities–your Electric Railway System.[4]

The new owners made a number of rapid changes. In 1946 they cut back the A-1 train route and then the express trains in 1947. The company increased fares in 1946 and then in both January and November 1947. During the period there were many complaints of overcrowding.[5]

On April 9, 1947, nine corporations and seven individuals (constituting officers and directors of certain of the corporate defendants) were indicted in the Federal District Court of Southern California on two counts: 'conspiring to acquire control of a number of transit companies, forming a transportation monopoly' and 'Conspiring to monopolize sales of buses and supplies to companies owned by National City Lines'.[6] They were convicted of conspiring to monopolize sales of buses and supplies. They were acquitted of conspiring to monopolize the ownership of these companies.

In 1948 they proposed a plan to convert all the streetcars to buses.[7] They placed an advertisement in the local papers explaining their plan to 'modernize' and 'motorize' Line 14.[8] Oakland city council opposed the plan by 5–3.[3] The Public Utilities Commission (PUC) supported the plan which included large fare increases.[7] In October 1948, 700 people signed a petition with the PUC "against the Key System, seeking restoration of the bus service on the #70 Chabot Bus line".[5] The councils of Oakland, Berkeley and San Leandro opposed the removal of street cars. The traffic planners supported removal of the streetcar lines to facilitate movement of automobiles.[3] Local governments in the East Bay attempted to purchase the Key System, but were unsuccessful.

In 1949 National City Lines, General Motors and others were convicted of conspiring to monopolize the sale of buses and related products to their subsidiary transit companies throughout the U.S.[9]

Between 1946 and 1954 transbay fares increased from 20¢ to 50¢. Fares in this period were used to operate and for 'motorisation' which included streetcar track removal, repaving, purchase of new buses and the construction of bus maintenance facilities. Transbay ridership fell from 22.2 million in 1946 to 9.8 million in 1952.[5]

The Key System's famed commuter train system was dismantled in 1958 after many years of declining ridership as well by the corrupt monopolistic efforts of National City Lines. The last run was on April 20, 1958. In 1960, the newly formed publicly owned AC Transit took over the Key System's facilities.

Most of the rolling stock was scrapped, with some sold to Buenos Aires, Argentina. Several streetcars, interurbans and bridge units were salvaged for collections in the United States. Of the large bridge units, three are at the Western Railway Museum near Rio Vista, California[10] while another is at the Orange Empire Railway Museum in southern California.

The Key System's first trains were composed of standard wooden railroad passenger cars, complete with clerestory roofs. Atop each of these, a pair of pantographs, invented and manufactured by the Key System's own shops, were installed to collect current from overhead wires to power a pair of electric motors on each car, one on each truck (bogie).

The design of rolling stock changed over the years. Wood gave way to steel, and, instead of doors at each end, center doors were adopted.

The later rolling stock consisted of specially designed "bridge units" for use on the new bridge, articulated cars sharing a common central truck and including central passenger entries in each car, a forerunner of the design of most light rail vehicles today. Several of these pairs were connected to make up a train. Power pickup was via pantograph from overhead catenary wires, except on the Bay Bridge where a third rail pickup was used. The Key's trains ran on 600 volt direct current, compared to the 1200 volts used by the SP commuter trains. The cars had an enclosed operator's cab in the right front, with passenger seats extending to the very front of the vehicle, a favorite seat for many children, with dramatic views of the tracks ahead.

The exterior color of the cars was orange and cream white with a pale green stripe at the window level. Interior upholstery was woven reed seat covers in one of the articulated sections, and leather in the other, the smoking section. The flooring was linoleum. During WWII, the roofs were painted gray for aerial camouflage. After acquisition by National City Lines, all Key vehicles including the bridge units were re-painted in that company's standard colors, yellow and green.

G – Westbrae Shuttle (actually, a streetcar shuttle providing a connection at University Avenue with the H transbay train)

H – Monterey Avenue (originally, the Sacramento Street Line; the original line ran up Hopkins, but was switched to the SP's old tracks up Monterey after 1933)

K – College Avenue (also a streetcar shuttle providing a connection at Alcatraz Avenue and Adeline Street with the F transbay train); this line ran extra cars and was heavily used on football game days as its terminus was only a few blocks away from UC's Memorial Stadium

The A, B, C, E and F lines were the last Key System rail lines. Train service ended on April 20, 1958, replaced by buses using the same letter designations. AC Transit preserved the letter-designated routes when it took over the Key System two years later, and are still in use; AC Transit's B, C, E, F, G and H lines follow roughly the corresponding Key routes and neighborhoods.

1911 map showing the various streetcar and commuter train lines that would later become the Key System

The Key System's streetcars operated as a separate division under the name "Oakland Traction Company", later changed to "East Bay Street Railways. Ltd", and finally to "East Bay Transit Co.", reflecting the increasing use of buses. The numbering of the streetcar lines changed several times over the years. The Key System's streetcars operated out of several carbarns. The Central Carhouse was on the east side of Lake Merritt on Third Avenue. The Western Carhouse was located at 51st and Telegraph Avenue in the Temescal District of Oakland. The Elmhurst Carhouse was in the east Oakland district of Elmhurst. The Northern Carhouse was in Richmond. In the early years of operation, these were supplemented by a number of smaller carbarns scattered throughout the East Bay area, many of them inherited from the pre-Key companies acquired by "Borax" Smith. The Key streetcars were painted dark green and cream white until they were re-painted in the green and yellow scheme of National City Lines after NCL acquired the Key System.[12]

The Key System had ordered 40 trolley coaches from ACF-Brill in 1945 to convert the East Bay trolley lines. The new NCL management canceled the Key's trackless program in 1946 before wire changes were made, and diverted the order (some units of which had already been painted for the Key and delivered to Oakland) to its own Los Angeles Transit Lines, where they ran until 1963.[13] The last Key streetcars ran on November 28, 1947, replaced by buses.[14]

The Eastshore and Suburban Railway (E&SR) was a formerly independent unit of the Key System which ran streetcar trains in Richmond, San Pablo, and El Cerrito. Service to Oakland required a transfer to Oakland Traction Company trains at the County Line station and service to San Francisco required an additional transfer.

See also the Sacramento Northern Railroad, an interurban system running from Chico through Sacramento to Oakland which also used some of the Key System's trackage as well as the Key System's ferry pier, and later ran to the Transbay Terminal until 1941.

From the beginning, the Key System had been conceived as a dual real estate and transportation system. "Borax" Smith and his partner Frank C. Havens first established a company called the "Realty Syndicate" which acquired large tracts of undeveloped land throughout the East Bay. The Realty Syndicate also built two large hotels, each served by a San Francisco-bound train, the Claremont and the Key Route Inn, and a popular amusement park in Oakland called Idora Park. Streetcar lines were also routed to serve all these properties, thereby enhancing their value. In its early years, the Key System was actually a subsidiary of the Realty Syndicate. Berkeley's numerous paths, lanes, walks and steps, were put in place in many of the newly developed neighborhoods, often in the middle of a city block, so that commuters could walk more directly to the new train system. Berkeley's pathways are still maintained by local groups.

The elevated loop at San Francisco's Transbay Transit Terminal, with some modifications to the original design, was used until the terminal's closure on August 6, 2010 by AC Transitbuses to drop off passengers and return to the East Bay as the Key System once did. The loop was completely demolished in 2010 and 2011 as part of the project to replace the old Transbay Terminal with a new structure scheduled for completion in 2018.[citation needed]

The south wall[15] of the lower level (today's eastbound lanes) of the Yerba Buena Tunnel, connecting the two spans of the Bay Bridge, still contains the as-built "deadman holes", regularly spaced nooks into which railway workers could duck whenever a train came along.[citation needed]

The tunnel that Key System trains used to cross under the Southern Pacific (now Union Pacific and Amtrak) tracks to the mole and later the Bay Bridge still exists. Is visible from the Alexander Zuckerman Bike Path and ramps of the Macarthur Maze.

A stretch of road in Albany that was built with a wide median for a planned extension (never constructed) of the "G" Westbrae line is named Key Route Boulevard.[citation needed]

The Claremont Hotel, built by a Key System affiliate company, The Realty Syndicate, survives as the Claremont Resort. It was the terminus of the "E" transbay line.[citation needed]

The Realty Syndicate Building at 1440 Broadway was built in 1912 and housed "Borax" Smith and Frank C. Havens's Realty Syndicate that created the Key System.[16] It is listed on the National Historic Register.[17]

A building which today houses a restaurant at 41st Street and Piedmont Avenue in Oakland is the partial remnant of what was formerly a covered stop for trains on the C-line. (The tracks followed 40th Street, crossed Howe Street and curved through the parking lot behind Piedmont Avenue shops, then merged onto Piedmont Avenue at 41st Street and headed toward Pleasant Valley Avenue.) Old photos of the Key System are on the walls of the restaurant, as well as a mural of Key System images on one of its outside walls. In December 2014, the mural was destroyed during renovation of the building. This act, apparently done swiftly and without public notice, has stirred considerable controversy [19]

The old Key System Piedmont shops building at Bay Place and Harrison is now a Whole Foods Market retail store. This building was originally built in 1890 as the powerhouse and car barn of the Piedmont Cable Car Co. In the 1920s, it was substantially remodeled and used as a Cadillac showroom which closed in the mid-1990s. The building sat vacant until 2003, when Whole Foods initiated a radical interior redesign while retaining and restoring much of the facade.[citation needed]

The bus yards of today's AC Transit in Emeryville and Richmond were originally the bus yards of the Key System. The Richmond yard was also previously the site of the Northern Carhouse of the Key streetcar system.[citation needed]

One of the 0-4-0 Steam locomotives used to push the trains during power outages is on display at the Redwood Valley Railroad. It had a brief stint on the currently re-constructing Virginia and Truckee Railroad in Virginia City, Nevada. Here, the mountain grades proved too taxing for the little locomotive. It was later replaced by 2–8–0 Steam locomotive No. 29.[21]

^"Paving the Way for Buses – The Great GM Streetcar Conspiracy Part II – The Plot Clots". Bay Crossings. May 2003. E. Jay Quinby, a mercurial rail fan, former electric traction employee, retired Lieutenant Commander in the Navy (World War II), and home builder of a battery-powered electric Volkswagen. His contribution to this story was to hand publish and expose the owners of National City Lines (GM, Firestone, and Phillips Petroleum) and he addressed it to "The Mayors; The City Manager; The City Transit Engineer; The members of The Committee on Mass-Transportation and The Tax-Payers and The Riding Citizens of Your Community." In 1946, he sent his 36-page analysis, which began: "This is an urgent warning to each and every one of you that there is a careful, deliberately planned campaign to swindle you out of your most important and valuable public utilities–your Electric Railway System."

^"United States Court of Appeals for the Seventh Circuit". 1951. Archived from the original on 2008-06-08. On April 9, 1947, nine corporations and seven individuals, constituting officers and directors of certain of the corporate defendants, were indicted on two counts, the second of which charged them with conspiring to monopolize certain portions of interstate commerce, in violation of Section 2 of the Anti-trust Act, 15 U.S.C.A. § 2.